Field of the Invention
Embodiments of the present invention relate to battery packs that can be detachably attached to tool bodies of electric tools or charger bodies of battery chargers.
Description of the Related Art
In recent years, some electric tools utilize battery packs configured as rechargeable batteries that can be detachably attached to tool bodies of electric tools. After having been attached to the tool main body and used, the battery pack may be detached from the tool body for recharging by a charger. The battery pack recharged by the charger may be attached to the tool body again for use. In the following, the tool body, the charger or the like to which the battery pack can be attached will be generally referred to as a “device body” Generally speaking, the battery pack may include an enclosure case also functioning as an outer case, and a battery unit disposed within the enclosure case. The battery unit may include a plurality of battery cells capable of recharging and discharging, and a circuit board for controlling the recharging and discharging of the plurality of battery cells. To this end, the circuit board may include positive and negative recharging/discharging terminals connected to the battery cells for the purpose of recharging/discharging of the battery cells, and signal terminals for transmitting and receiving signals to and from the tool body or the charger to which the battery pack is attached (see, for example, JP-A-2008-10315).
The recharging/discharging terminals and signal terminals may be formed as female terminals allowing connection with male terminals provided on the device body such as the tool body or the charger. The male terminals may have shapes of flat plates. The female terminals may be configured to receive and hold the flat-plate-shaped male terminals. The male terminal may be moved to the direction in which they extend so as to be slid into and held between the female terminals to provide electrical contacts. The electrical contacts may allow transmission and reception of electric power or transmission and reception of communication signals. The recharging/discharging terminals and signal terminals provided on the battery pack will be generally referred to as “(holding type) battery side terminals.” The male terminals on the device body side for connection to the female connection terminals will be generally referred to as “(flat-plate type) device side terminals.”
The battery pack may receive an operational shock during the operation of an electric tool or may receive vibrations due to the driving of the electric tool. It may be possible that the battery side terminals receiving such a shock and vibration cause simultaneous resonance in both the electrical contact portions. Such simultaneous resonance of both the electrical contact portions may impair the reliability with regard to the electrical connection with the device side terminals.
Therefore, there has been a need of ensuring reliable electrical connection of the battery side terminals with the device side terminals.
According to a first aspect of the disclosure, a battery pack may be detachably mounted to a device body of an electric tool or a charger. The battery pack may include a battery side terminal connectible with a device side terminal. The device side terminal may be configured to have a shape of a flat plate and may have a first side surface and a second side surface opposite to each other. The battery side terminal may include a first contact portion and a second contact portion. The first contact portion may be configured to form an electric contact through contact with the first side surface of the device side terminal. The second contact portion may be configured to form an electric contact through contact with the second side surface of the device side terminal. The first contact portion may contact the first side surface in a first contact range having a first length. The second contact portion may contact the second side surface in a second contact range. The second length may be different from the first length.
By setting the second length to be different from the first length, it may be possible to prevent the first and second contact portions from simultaneously resonate when the battery pack receives an operational shock during the operation of the electric tool or receive vibrations due to the driving of the electric tool. Hence, it is possible to ensure the electric connection through at least one of the electric contacts formed by the first and second contact portions. As a result, it is possible to ensure the electric connection between the battery side terminal and the device side terminal.
The battery side terminal may further include a third contact portion and a fourth contact portion. The third contact portion may be configured to form an electric contact through contact with the first side surface of the device side terminal. The fourth contact portion may be configured to form an electric contact through contact with the second side surface of the device side terminal. The third contact portion may contact the first side surface in a third contact range having a third length. The fourth contact portion may contact the second side surface in a fourth contact range having a fourth length.
In one embodiment, the third length is different from the first length and/or the fourth length is different from the second length. With this arrangement, it may be possible to prevent the first and third contact portions and/or the second and the fourth contact portions from simultaneous resonance. Hence, it is possible to further ensure the electric connection between the battery side terminal and the device side terminal.
In another embodiment, the first contact portion and the fourth contact portion are arranged diagonally to each other, and the fourth length is the same as the first length. Additionally or alternatively, the second contact portion and the third contact portion are arranged diagonally to each other, and the third length is the same as the second length. With this arrangement, it is possible to achieve the contact balance between the first contact portion and the fourth contact portion and/or between the second contact portion and the third contact portion. In addition, it is possible to set such that the contact force applied to the first side surface and the contact force applied to the second side surface are nearer to each other. As a result, it is possible to achieve a balance in the contact forces applied to the device side terminal.
In a further embodiment, the first contact portion and the fourth contact portion are arranged to be opposed to each other, and the fourth length is the same as the first length. Additionally or alternatively, the second contact portion and the third contact portion are arranged to be opposed to each other, and the third length is the same as the second length. With this arrangement, it is possible to achieve the contact balance between the first contact portion and the fourth contact portion and/or between the second contact portion and the third contact portion. In addition, it is possible to set such that the contact force applied to the first side surface and the contact force applied to the second side surface are nearer to each other. As a result, it is possible to achieve a balance in the contact forces applied to the
The battery pack may include a plurality of battery side terminals each connectible with a corresponding device side terminal.
According to a second aspect of the disclosure, a battery pack may be detachably mounted to a device body of an electric tool or a charger. The battery pack may include a battery side terminal connectible with a device side terminal. The device side terminal may be configured to have a shape of a flat plate and may have a first side surface and a second side surface opposite to each other. The battery side terminal may include a first contact portion and a second contact portion arranged so as to be opposed to each other. The first contact portion may be configured to form an electric contact through contact with the first side surface of the device side terminal. The second contact portion may be configured to form an electric contact through contact with the second side surface of the device side terminal. The first contact portion may contact the first side surface in a first contact range having a first length. The second contact portion may contact the second side surface in a second contact range.
The battery side terminal may further include a third contact portion and a fourth contact portion arranged so as to be opposed to each other. The third contact portion may be configured to form an electric contact through contact with the first side surface of the device side terminal. The fourth contact portion may be configured to form an electric contact through contact with the second side surface of the device side terminal. The third contact portion may contact the first side surface in a third contact range having a third length. The fourth contact portion may contact the second side surface in a fourth contact range having a fourth length. The third length may be different from the first length and/or the fourth length may be different from the second length.
In one embodiment, the second length may be the same as the first length, and the fourth length may be the same as the third length.